Interesting topic. The first thing to know is any issues due to not following break-in would be in the long term, in the form of decreased engine/tranny/diff life, but it's almost impossible to quantify. No demo car ever follows break-in rules, and they're sold as 'new' cars, with full warranties.

Issues commonly related to a bad break-in are increased oil consumption, a 'whiny' differential, to a less extent 'whiny' transmission, and decreased engine life, which is very subjective.

In my opinion, break-in is speficied in the US more for legal reasons than mechanical ones, as some identical cars don't specify a break-in period in Europe but they do in the US. Basically the manufacturer wants the driver to get familiar with the car before going crazy, which is also a good idea for the brakes, clutch, differential, transmission, and engine, but how much (if at all) those components are affected without proper break-in is an issue that's impossible to prove. I mostly follow it because I want to be familiar with the car before pushing it, and also makes me feel good that I'm taking steps to maximize the life of my car overall, since driving in that manner means no gear grinding (for 6MTs), no clutch glazing, no brake squealing (due to glazed rotors), etc.

But what's more important to me is how you take care of the car all the time, like no speed-shifting, no hard throttle until oil is at operating temperature, etc. Good day gang.

Interesting topic. The first thing to know is any issues due to not following break-in would be in the long term, in the form of decreased engine/tranny/diff life, but it's almost impossible to quantify. No demo car ever follows break-in rules, and they're sold as 'new' cars, with full warranties.

Issues commonly related to a bad break-in are increased oil consumption, a 'whiny' differential, to a less extent 'whiny' transmission, and decreased engine life, which is very subjective.

In my opinion, break-in is speficied in the US more for legal reasons than mechanical ones, as some identical cars don't specify a break-in period in Europe but they do in the US. Basically the manufacturer wants the driver to get familiar with the car before going crazy, which is also a good idea for the brakes, clutch, differential, transmission, and engine, but how much (if at all) those components are affected without proper break-in is an issue that's impossible to prove. I mostly follow it because I want to be familiar with the car before pushing it, and also makes me feel good that I'm taking steps to maximize the life of my car overall, since driving in that manner means no gear grinding (for 6MTs), no clutch glazing, no brake squealing (due to glazed rotors), etc.

But what's more important to me is how you take care of the car all the time, like no speed-shifting, no hard throttle until oil is at operating temperature, etc. Good day gang.

Blows up how, from the bullshit story about the car running while puting gas in, or from the bullshit story about not breaking it in up to 3K?
Or maybe it was the bullshit story about static electricity and exhaust fumes?

Was told by M division engineers that a 1200 mile break in for the rear differentail & manual transmission is more critical than for the engine and then a fluid change.

M division engineers called you in Ontario to discuss trannies and diffs? Ok, I'll play along. I could only imagine that the reasoning would be that IF there were a problem, damage would be minimal ($$) and easily repaired as opposed to damage that takes place under full throttle. By no means though, do gears have a break-in period.

Yea, I realize that the car won't blow up, the warranty won't be void, and that this is a REPOST, hence my disclosure in the first post. However, still curious, does anyone have any experience with a car that wasn't broke in properly? How differently does it handle? When I got the car, it was low on oil, kinda pissed me off, anyway, would my car run through oil faster? That doesn't even make sense.

M division engineers called you in Ontario to discuss trannies and diffs? Ok, I'll play along. I could only imagine that the reasoning would be that IF there were a problem, damage would be minimal ($$) and easily repaired as opposed to damage that takes place under full throttle. By no means though, do gears have a break-in period.

Yes - gears have a break in period. Diffs do need to be broken in. Careful who you "play along" with. He never said anything about being on the phone. He was however in Germany at BMW and had some time at M division - so there might be a correlation.....

But I do understand why you be skeptical given some of the stuff posted on this board.

M division engineers called you in Ontario to discuss trannies and diffs? Ok, I'll play along.

Unbelievable. We here in Ontario have telephones, the internet and yes, even airplanes. Once in awhile we're even given travel permits so that we can visit people and places "on the outside", provided of course that we trust our government enough to detain our families comfortably until we return.

That aside, all this info has been helpful. Didn't break in the 135 gently, in fact it was broken in (with only 450 km's on the odo) at Watkins Glen (yes Kyoshi, had to travel to New York for this but I have friends in high places who helped me in) and its been perfect since. I plan to do the same for the soon to be M3 but I'll pay attention to turb934's advice (and all of the other posts regarding this issue) which generally suggest a common sense "mix" of driving ranges.

Unbelievable. We here in Ontario have telephones, the internet and yes, even airplanes. Once in awhile we're even given travel permits so that we can visit people and places "on the outside", provided of course that we trust our government enough to detain our families comfortably until we return.

That aside, all this info has been helpful. Didn't break in the 135 gently, in fact it was broken in (with only 450 km's on the odo) at Watkins Glen (yes Kyoshi, had to travel to New York for this but I have friends in high places who helped me in) and its been perfect since. I plan to do the same for the soon to be M3 but I'll pay attention to turb934's advice (and all of the other posts regarding this issue) which generally suggest a common sense "mix" of driving ranges.

OMG! They let you out? What is this world coming to? And who are these people in New York? I'll see to it that the DHS, FBI, and USMC get on it right away. We cannot allow this to happen in USA. New York is in the USA, isn't it? Never mind.

Achtung! This is a public message for those of you who break-in their new BMW improperly:

OMG! They let you out? What is this world coming to? And who are these people in New York? I'll see to it that the DHS, FBI, and USMC get on it right away. We cannot allow this to happen in USA. New York is in the USA, isn't it? Never mind.